Novel Zeolite-like Forms of Zinc and Cobalt Imidazolate

Categories: “Chemistry

Reference: # 2016-054

OTC Contact: Zeinab Abouissa M.S.
Phone: 202-687-2702


Zeolitic metal-organic frameworks (Z-MOFs) —e.g., metal pyrimidines, zeolitic/tetrahedral imidazolate frameworks (ZIFs,/TIFs), boron imidazolate frameworks (BIFs) have received considerable attention as expanded, metal-organic analogs of zeolites for sorption-related applications due to their high porosity, chemical and structural diversity, and their relative stability. In principle, the ZIF compositions derived from imidazolate ligands with minimal steric demands (i.e., unsubstituted imidazolate, Im-) have the greatest potential for net topological diversity. To date, for example, the simple Zn(Im)2 composition has been observed to exist in several different network topological forms. The most important ZIFs, however, will be those that are available in large quantities while offering useful performance metrics (e.g., high porosity, large/uniform pore diameter, stability). However, none of the highest porosity forms of Zn(Im)2 have been amenable to large-scale synthesis.

Figure 1. Crystal structure of GME-Zn(Im)2×xsolvent (solvent omitted, mean ligand positions). Left: [010] view. Right: [001] view.  The d6r and gme cages and the 12-ring kno channel are indicated.

Researchers at Georgetown University’s Department of Chemistry have successfully synthesized the novel porous, crystalline gmelinite (GME) polymorphic form of Zn(Im)2 (Porosity = 0.66, Figure 1), in near-quantitative yield and at hectogram scale, by employing a bulky solvent/SDA with a globular shape and exceptional hydrogen bonding properties. This was achieved in a low cost and easy to manufacture process. GME-Zn(Im)2 is the lowest density form of Zn(Im)2 isolated to date, exhibits an exceptionally high ZIF surface area (1842(77) m2/g), and is the first reported GME net topology ZIF synthesized at hectogram scale. Further, the researchers were able to produce GME-Co(Im)2 which also exhibits excellent stability. ZIFs of the GME topology generally exhibit high chemical/thermal stability, high permanent porosities, and are good candidates for commodity gas separations and other industrial applications.


Provisional patent application filed


Travis Holman Ph.D., Professor
Department of Chemistry